The invention concerns a method of producing and/or maintaining a wake mode in a receiving module of an electronic installation as claimed in claim 1, which in addition to the receiving module also has a transmitting module that is connected through an optical bus system.
Integrated information and communication devices in automobiles, or also navigation devices which are examples of electronic installations in conjunction with this application, for reasons of space are often divided into two or more modules since the user interfaces must be within reach of the driver but the entire information and communication device cannot be installed there. For that reason the largest part of the installation is often placed elsewhere, e.g. in the trunk or the rear of the vehicle. In that case the individual modules are interconnected by an optical bus system for reasons of weight and electromagnetic compatibility. However the power consumption of the module when the automobile""s ignition is turned off is relatively high and can be higher than a predetermined minimum limit value provided by the automobile industry, which is not desirable. On the other hand, all modules must be able to activate each other in spite of the turned off automobile ignition.
It has already been proposed to install an electrical cable in parallel with the bus system for automobile modules which are interconnected by an optical bus system. The individual modules are completely switched off when the automobile ignition is turned off. A wake-up signal is transmitted through the electrical cable to reactivate these modules.
However the additional electrical cable between the modules creates higher cable and installation costs and increases the total weight of the concerned installation. On the other hand a galvanic connection exists between the modules, which is unfavorable from the electromagnetic compatibility""s point of view and partially cancels the advantages of the optical bus system, particularly in regard to the galvanic uncoupling.
For that reason and to eliminate these problems, DE-A-19708979 proposes an electronic device control which works without a galvanic connection between the modules, and where the optical bus system is exclusively used to establish the wake mode between the modules. It indicates:
that in the power saving mode of each module the same scanning period is used for all the modules and a smaller scanning time interval is switched to receiving;
that one of these modules provides an interrupt signal to the optical bus system, whose duration is equal to or longer than the scanning period; and
that at least one other of these modules is switched to permanent reception when it receives the interrupt signal during the next scanning time interval.
Even if the known method or the known device can work without an electrical connection to produce the wake mode, it is necessary to provide a control arrangement which switches the module to active during the scanning interval so that the optical interrupt signals can be transmitted or detected. The known arrangement furthermore does not create a full power saving mode, because the respective optical transmitters or receivers must be switched to active during the scanning interval.
It is therefore the invention""s objective to provide a power saving mode for modules that are connected by an optical bus system, where the periodic inquiries of the different modules and the involved disadvantages do not occur, and which is only turned off so that an actual data exchange can take place between the modules.
This object is achieved by a method of establishing and/or maintaining a wake mode for an electrical installation, which in addition to at least one receiving device has at least one transmitting device that is connected through an optical bus system, characterized by the following steps: that in the first step the respective transmitting device provides optical signals to the optical bus system to establish and/or maintain the wake mode in the respective receiving device, that in a second step the optical signals arriving in the receiving device strike a converter equipped with a photo-sensitive layer, and that in a third step the optical signals striking the layer are used to supply energy to the receiving device.
The invention particularly points out that during the sleep mode no power is consumed by the transmitting and receiving devices of the components which are only connected by the optical bus system. This ensures possibilities of lengthy operation in the case of battery-supported arrangements, and saves power in network-supported arrangements.